1. Field of the Invention
The present invention relates to a pattern forming method, to an image forming method, a fine particle adsorption pattern forming method, and a conductive pattern forming method, in which substances having various functionalities are adhered in a pattern shape as applications of the pattern forming method, and to a pattern forming material and a planographic printing plate prepared by the pattern forming method.
2. Description of the Related Art
Techniques for forming a fine pattern have recently attracted attention in various fields. In particular, methods for forming fine hydrophilic/hydrophobic patterns have attracted attention. For example, as a method of forming hydrophilic/hydrophobic patterns, there is a known technique of forming a pattern having hydrophilic/hydrophobic zones by forming a stamp having a convex pattern on a surface, adhering hydrophobic molecules on the convex pattern portion, then transferring the hydrophobic molecules onto a substrate, and adhering hydrophilic molecules on a portion of the substrate to which the hydrophobic molecules have not been transferred (for example, see Japanese Patent Application Laid-Open (JP-A) No. 2002-283530). The hydrophilic/hydrophobic pattern thus prepared is useful for various functional devices, DNA chips and the like. However, although fine and precise patterns can be formed according to the technique, a specific material must be used, and it has been difficult to apply the method to large area image formation and the like.
As a technique related to application to large area image formation, there is a known method of forming a pattern (an image portion and a non image portion) comprising a hydrophilic layer and a hydrophobic substrate surface, by forming the hydrophilic layer comprising a hydrophilic graft polymer on the whole surface of the hydrophobic substrate, and then removing imagewise the hydrophilic layer from the substrate surface by abrasion by laser exposure (for example, see JP-A No. 11-119413). Since the step of transferring the pattern is not required according to the method, it can be used as a large area planographic printing plate material by adhering water and an ink on the prepared hydrophilic/hydrophobic pattern. However, the method of forming the hydrophilic/hydrophobic pattern requires an expensive high power laser because high energy is required for removing the hydrophilic layer, and further, the quality and the resolution of the formed image are also unsatisfactory.
As methods of forming patterns by lower energy in response to this problem, there is a known method of preparing a hydrophilic/hydrophobic pattern, by forming a preparation portion and a non preparation portion of a graft polymer through the steps of 1. cross-linking a polystyrene film using γ-rays, 2. chloromethylating a styrene unit portion, 3. bonding dithiocarbamate on a film surface and bonding a photo-polymerization initiator on the film surface, and 4. immersing the film in a monomer solution and carrying out imagewise active beam irradiation (for example, see “Langmuir, Volume 15” by Takehisa Matsuda, et. al, 1999, pp. 5560-5566). However, there are problems in that this method requires 4 steps for forming the hydrophilic/hydrophobic pattern and the work is troublesome.
As a technique of applying the hydrophilic/hydrophobic pattern, there is a technique of arranging fine particles in a pattern shape. The technique of arranging fine particles is an important technique for achieving higher functions such as larger area, higher resolution and higher density of materials such as catalysts, recording materials, sensors, electronic devices and optical devices, and thus, studies thereon have been carried out extensively.
For example, a method of forming the aggregated fine particles is proposed in which a liquid dispersion medium of fine particles is developed on a substrate to form a liquid thin film, the liquid thickness of the liquid dispersion medium is reduced and controlled to a liquid thickness equal to or thinner than the particle size, and the fine particles are aggregated by use of surface tension (for example, see Japanese Patent No. 2828374). According to the method, a layer of fine particles can be evenly aggregated and uniformly arranged, but it is difficult to obtain a patterned arrangement in a desired zone.
Further, as a technique of arranging fine particles in a pattern shape, there is a known method in which a surface of an oxide substrate such as TiO2 is irradiated with light in a pattern shape, a hydrophilic pattern is formed on the surface, and the fine particles are arranged in accordance with the pattern (for example, see JP-A No. 2002-273209). According to the method, it is possible to prepare a pattern of fine particles, but since the fine particles are merely physically adhered and not fixed, they are easily released, and the pattern is not suitable for uses as various devices. Further, particles also tend to be adhered to a portion other than the pattern where the fine particles are adhered, and there is a desire for a method of forming a pattern having high selectivity where particles are not adhered on a portion other than the pattern.
As another method of arranging fine particles in a pattern shape, there is a known method of laminating pattern-shaped fine particles using the micro stamp of G. M. Whitesides et al. (for example, see E. Kim, Y. Xia, G. M. Whitesides, “Advanced Materials” Vol. 8, Wiley Interscience, 1996, page 245). According to the method, polymer fine particles with a sub micron size can be accumulated in order with certainty, and a method of forming a pattern having high selectivity where particles are not adhered on a portion other than the pattern can be provided. However, since the procedure of the method is difficult and the solvent evaporation rate must be controlled for preparing ordered particle laminates, the particle laminates cannot be easily prepared. Further, since an area capable of being prepared is small, this method is not suitable for preparing a laminate with a large area. Furthermore, adsorption strength between a substrate and fine particles laminated in a pattern shape is weak. Therefore from the viewpoint of practical use, high adsorption strength between the substrate and the fine particles is required.
On the other hand, finer conductive materials (conductive pattern) are required in accordance with the size reduction of electric home products. Typically, such conductive pattern material is obtained by providing a thin film conductive material which is formed by known methods such as vacuum evaporation on an insulator, treating it with a resist, removing the portion of the resist preliminarily prepared by pattern exposure, and then carrying out etching treatment to form a desired pattern. Accordingly, it requires at least four steps, and when wet etching treatment is carried out, a step for disposal the waste solution is also required. Therefore a complicated process has to be carried out.
Then, there has been recently developed a method of drawing a metal paste containing metal fine particles on a substrate by ink jet, as a method of forming conductive patterns (for example, see JP-A No. 2002-324966). However, the method has problems in preparing conductive fine patterns in that fine patterns having an order of several microns cannot be prepared because of the drawing by ink jet, and in that, while patterns having an order of several tens of microns can be prepared, conductivity is unstable because of low viscosity of the metal paste and difficulty in lamination, etc. Further, since the conductive layer which is drawn is only set on the substrate, there have also been problems with respect to adhesion property between the substrate and the conductive layer.